Lab 6 experiments

Proteins are digested by

pepsin

What is Biuret reagent

a chemical test that detects the presence of peptide bonds.

positive biuret test

purple

negative biuret test

blue

Which solution had the greatest amount of protein digestion?

test tube 1: 3ml of pepsin +HCl (HCl broke down the most peptide bonds)

Broken down lipids (triglycerides) form

monoglycerides and fatty acids

What enzyme breaks down lipids

pancreatic lipase

The separation of large aggregates of fat into smaller droplets is termed

emulsification

What emulsifies lipids?

bile salts

What is phenol red?

PH indicator; red = neutral PH 7; yellow = acidic;

Lipid emulsification experiment - pink color

No lipid digestion

Lipid emulsification experiment - Red/orange color

Some digestion

Lipid emulsification experiment - Yellow color

Significant lipid digestion

Which tube from the experiment showed the most LIPID DIGESTION

Tube 2: 3ml of olive oil, phenol red, lipase, bile salts. ( lipase was able to work because lipids were emulsified)

Where does the acid come from during lipid digestion?

The fatty acids from the broken down lipids.

Many of the carbohydrates in our diet are in the form of

starch

What does salivary amylase do?

digests starch into maltose

what is Lugol's iodine used for?

indicates starch (carbohydrates)

A positive indication of starch from the lugol's iodine test is what color?

dark blue

A negative indication of starch from the lugol's iodine test is what color?

Brownish

What is Benedict's solution?

a standard test for sugar

Positive indicator for Benedict's solution looks like what?

A change in color (yellow, green, orange, or red)

Negative indicator for Benedict's solution looks like what?

No change in color; remains blue

Why did the test tube containing salivary amylase show a negative result for the lugol's iodine test?

The salivary amylase should have broken down the starch during incubation, resulting in no indication of starch.